题型:填空题 This machine is very easy _______. Anybody can learn to use it in a few minutes. A.operating B.to be operating C.operated D.to operate 查看答案
题型:填空题 在生产性毒物危害治理的措施中,通风防毒工程的一个重要的技术准则为( )。A.就地密闭,就地排出,就地净化B.就地密闭,就地排出,就地排毒C.就地排出,就地净化,就地回收D.就地排出,就地回收,就地净化 查看答案